Contamination & Controls

EVP / ITC Experimentation · 04

Radio bleed, human speech, movement noise, recorder handling, room acoustics, expectation bias, and review discipline.

ACS SA Lab spectral and waveform analysis — SA Lab represents the discrimination layer: waveform and spectral review can support questions, but it does not magically prove source or meaning.

Mark human noiseEvery cough, chair movement, whisper, footstep, or device touch should be called out during recording.

Check the roomHVAC, appliances, traffic, radio, plumbing, neighbors, insects, and building sounds can create false candidates.

Blind review helpsDo not lead reviewers with the phrase you expect. Let them report what they hear independently.

Lesson Reading

Contamination Is Normal

Contamination is not failure. It is part of audio and ITC work. The mistake is pretending contamination is not possible. Every session should assume ordinary sources may be present until they are checked.

Useful Controls

Use baseline room tone, no-question control periods, device-distance notes, spoken event markers, multiple recorders when possible, and review copies that preserve the raw original. For radio or sweep work, document frequencies, sweep rate, nearby stations, and any audible broadcast fragments.

Expectation Bias

People hear what they are prepared to hear. That does not make every candidate meaningless, but it does mean review should be patient. Ask reviewers for independent impressions before sharing your own interpretation.